Apparatus for detecting spin of golf ball in indoor golf playing system

ABSTRACT

In an indoor golf playing system, it is very advantageous if a golfer can determine the amount of side spin, i.e., slice or hook imparted to the ball. The ball is placed at a known point which is part of the indoor system and is hit into an impact surface such as a wall or screen which displays a picture of an appropriate portion of a golf course as it is seen by a golfer. A row of detectors is positioned in front of the impact surface and, as the golf ball is hit toward the surface and crosses the row of detectors, it actuates one or more of the detectors to produce an output. In this manner, the path of the ball travelling towards the surface is detected. The ball, upon hitting the surface, rebounds back toward the golfer and is again detected by one or more of the detectors as it passes back through the row of detectors. The angle at which the ball rebounds from the surface is a function of the side spin imparted to the ball by the golfer. Therefore, by detecting the point at which the ball crosses the row of detectors as it travels toward the surface and comparing this point to the point at which the ball travels through the row of detectors as it rebounds from the surface, the amount of side spin can readily be determined. In the event the golf ball is to be hit from points of origin that may not be determined, a second row of detectors may be positioned between the first row of detectors and the points of origin.

United States Patent 1 1 Angelos Sept. 24, 1974 APPARATUS FOR DETECTING SPIN OF GOLF BALL IN INDOOR GOLF PLAYING SYSTEM [76] Inventor: Arthur C. Angelos, 8202 Langbrook Rd., Springfield, Va. 22152 [22] Filed: Mar. 13, 1973 [21] Appl. No.: 340,648

Primary Examiner-George J. Marlo [57] ABSTRACT In an indoor golf playing system, it is very advantageous if a golfer can determine the amount of side spin, i.e., slice or hook imparted to the ball. The ball is placed at a known point which is part of the indoor system and is hit into an impact surface such as a wall or screen which displays a picture of an appropriate portion of a golf course as it is seen by a golfer. A row of detectors is positioned in front of the impact surface and, as the golf ball is hit toward the surface and crosses the row of detectors, it actuates one or more of the detectors to produce an output. In this manner, the path of the ball travelling towards the surface is detected. The ball, upon hitting the surface, rebounds back toward the golfer and is again detected by one or more of the detectors as it passes back through the row of detectors. The angle at which the ball rebounds from the surface is a function of the side spin imparted to the ball by the golfer. Therefore, by detecting the point at which the ball crosses the row of detectors as it travels toward the surface and comparing this point to the point at which the ball travels through the row of detectors as it rebounds from the surface, the amount of side spin can readily be determined. In the event the golf ball is to be hit from points of origin that may not be determined, a second row of detectors may be positioned between the first row of detectors and the points of origin.

10 Claims, 3 Drawing Figures 'PATENIED SEW-41974 SHEET 1 [If 2' APPARATUS FOR DETECTING SPIN OF GOLF BALL IN INDOOR GOLF PLAYING SYSTEM BACKGROUND OF THE INVENTION This invention relates to an apparatus for detecting the amount of spin imparted to a golf ball in an indoor golf playing system and, more particularly, to such an apparatus using an impact surface such as a screen and a row of detectors spaced from the impact surface.

Several prior art devices exist for determining the amount of hook or slice imparted to a golf ball in an indoor golf playing system. These devices, however, have not been completely satisfactory in that they have been complicated in construction and expensive to manufacture, have required complex screen arrangements, have not been completely accurate or reliable in operation, and have required extensive maintenance.

In one such device, a spherical shell or screen is used and the tee for the golf ball is positioned at the center of the sphere. If the golf ball is hit without side spin, it will hit the screen and rebound therefrom to the center of the sphere. If however, a side spin is imparted to the ball, it will not return to the center of the sphere. By measuring or indicating the point to which the ball returns, the amount of spin (hook or slice) can be determined. This type of system is subject to certain disadvantages. If the ball must roll back towards the center of the sphere before its rebound position is indicated, it is subject to inaccuracies caused by the floor surface not being completely level which may affect the roll and/or bounce of the ball. Furthermore, the construction of a perfectly spherical screen is difficult and expensive.

Another type of device uses two impact surfaces or screens positioned at an angle to each other. The ball is hit into one of the screens and bounces off of that screen onto the second screen. The points at which the ball strikes the first and second screens are detected to indicate the amount of spin imparted to the ball. The geometry of the two screens is such that if a ball having no side spin strikes the first screen at a first point, it will strike the second screen at a predetermined second point. If, however, side spin is imparted to the ball, it will strike the second screen at a point other than the predetermined second point, and the difference between the actual second point of contact and the predetermined point is used to determine and indicate the amount of hook or slice. This system has the obvious disadvantage that it requires two accurately positioned and constructed screens rather than a single screen. This is critical not only because of the additional expense of a second screen but also because of the additional space required for the second screen. Space, of course, is at a premium in an indoor golf playing system. Also, the second screen may adversely affect, from the standpoint of appearance, the simulation of actual golf course playing conditions.

A third type of apparatus uses a single screen wound on two cylinders such that, as it is wrapped around one cylinder, it unwraps from the other cylinder. If a ball having a side spin is hit into the screen, it will move the screen laterally in a direction corresponding to the direction of the spin and in an amount corresponding to the amount of spin. By detecting the amount of screen which is unwrapped from one cylinder and wrapped around the other cylinder, owing to the impact of the spinning golf ball, the amount of spin and thus the amount of slice or hook can be determined and indicated. This type of apparatus has the disadvantage of being expensive and complicated in construction in that it requires two cylinders and the mechanism associated therewith for wrapping and unwrapping the screen. Furthermore, the moving parts in the screen mounting mechanism are subject to wear and thus to mechanical failure, thus requiring extensive maintenance.

SUMMARY OF THE INVENTION It is a primary object of the present invention to provide an apparatus for detecting the amount of spin imparted to a golf ball in an indoor golf playing system.

It is another object of this invention to provide an apparatus for detecting the amount of spin imparted to a golf ball, which includes an impact surface such as a wall or screen and a row of detectors positioned between the point from which the golf ball is hit and the impact surface for detecting the path of the ball as it is hit towards the surface and after it rebounds from the surface, thereby detecting and indicating the amount .of spin imparted to the ball.

The present invention is directed to an apparatus for detecting the amount of spin, e.g., slice or hook imparted to a golf ball in an indoor golf playing system such as that disclosed in US. Pat. No. 3,559,996 which is incorporated herein by a reference. The apparatus includes an impact surface such as a wall or screen into which the golf ball is hit. A row of detectors is positioned between the point from which the ball is hit and the surface. After the ball has been hit and prior to striking the surface, it crosses the row of detectors to actuate one or more of them. The ball then rebounds from the surface and crosses back through the row of detectors to actuate one or more of them. In the case of a substantially planar impact surface, if the ball has no spin imparted to it, the angle of incidence of the ball with respect to the impact surface will equal the angle of reflection. Thus, when there is no spin on the ball and it is detected by one or more detectors as it travels towards the surface, there is a corresponding known detector or detectors which should be actuated as the ball rebounds from the surface. If side spin is imparted to the ball, the actual angle of reflection from the surface will differ from the angle of reflection when there is no side spin. Therefore, a ball having side spin will actuate one or more detectors other than the" known detector or detectors which would be actuated when there is no side spin. By noting which detector (or de tectors) is actuated by the reflected ball having side spin, the amount of hook or slice can readily be deter-v mined and indicated.

As an illustrative example, one means for detecting the amount of spin imparted to a golf ball comprises'a voltage divider having a plurality of sections with switches, corresponding to each section, connected to the detectors. When a golf ball crosses the row of detectors and actuates one of them, the corresponding switch is closed, thus setting up a particular voltage divider. The voltage across the voltage divider, therefore, corresponds to the detector or detectors actuated by the golf ball. The detecting means also includes a capacitor for storing the voltage corresponding to the detector or detectors actuated as the ball travels toward the impact surface, and another capacitor for storing the voltage corresponding to the detector or detectors actuated by the rebounding golf ball. The voltages stored on the two capacitors are compared so as to produce an output indicative of the amount of spin imparted to the golf ball.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing the angles of reflection for various angles of incidence of a golf ball, relative to a substantially planar impact surface, in order to illustrate generally the principles of the present invention;

FIG. 2 is a schematic plan view showing the positioning of the impact surface and row of detectors in the apparatus of the present invention; and

FIG. 3 is a schematic view and circuit diagram of a preferred form of detecting and indicating means of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, if a ball at point 2 is hit into a substantially planar impact surface 4 such as a wall or screen, the ball will rebound from the impact surface at an angle determined, at least in part, by the angle of incidence. If there is no side spin on the ball, then the angle of reflection from the surface 4 will equal the angle of incidence of the ball onto the surface. Three paths, A, B and C, are illustrated in FIG. 1. In approach path A, for example, if there is no spin on the ball, the ball will be reflected by surface 4 and will follow return path Al. The angles between approach path A and surface 4, and return path A1 and surface 4, are substantially equal and are designated a. If, however, the ball has a clockwise side spin or slice imparted to it, the angle of reflection will be smaller than the angle of incidence and the golf ball will follow return path A3. If the clockwise spin or slice is even greater, then the ball will follow the return path A Similarly, if the ball has a counterclockwise spin or hook imparted to it, then the angle of incidence will be less than the angle of reflection and the reflected ball will follow return path A2 shown in FIG. 1. Paths B and C in FIG. 1 illustrate the effects of hooking and slicing for different angles of incidence.

FIG. 2 illustrates the incorporation of the side spin detecting apparatus of the present invention in an indoor golf playing apparatus such as that disclosed in US. Pat. No. 3,559,996. The golf ball is hit from a known point 6 towards the impact surface 9, which may be of any suitable construction and preferably is a substantially planar wall or screen. A row of detectors of any suitable type is positioned between the point 6 and the impact surface 9 for detecting the position of the golf ball as it approaches the surface and as it rebounds from the surface. The spacing and arrangement of the detectors 10 will depend on the degree of resolution desired. As an illustrative example, a row of 32 photo detectors 10 may be used, and light sources 12 may be provided to illuminate the photo detectors 10. The light sources 12 preferably are non-visible, such as infra-red, so that there is no distraction to the player hitting the golf ball from the point 6.

The photo detectors 10 may be of any suitable type such as photo diodes, photo transistors, photo multipliers or any other devices which produce an output signal in response to a change in light incident on the device. It is to be readily understood, however, that any suitable type of detection means, other than lightresponsive means, may be utilized within the scope of the present invention.

In the use of the apparatus of the present invention, as the ball travels from the point 6 to the surface 9, it crosses the row of photo detectors 10 and blocks the light from the light sources 12 to one or more of the photo detectors to actuate them, thus producing a signal at the output of the blocked photo detector or detectors. In the example shown in FIG. 2, photo detector 16 is actuated by the ball as it travels toward the impact surface 9. After striking the surface 9, the ball rebounds therefrom and again crosses the row of photo detectors 10 to actuate another one (or more) of the photo detectors by momentarily cutting it off from its light source 12. If the ball is hit without side spin, the angle of incidence with respect to a substantially planar surface 9 will equal the angle of reflection. By knowing the location of the point 6 from which the ball is hit, the location of the point of contact 15 on the surface 9, and the photo detector 16 (or detectors) which is actuated by the ball travelling from point 6 to point 15, the photo detector to be actuated by the rebounding ball, if the ball were hit without side spin, can be predicted. If, however, the rebounding ball actuates a photo detector or detectors other than the photo detector 14, this indicates that the ball had side spin when it hit the point 15 on the surface 9.

As is well known, for a right-handed golfer, when a golf ball is sliced, the side spin imparted to it is clockwise, and when a golf ball is hooked, the side spin is counterclockwise. As illustrated in FIG. 2, if the ball were hooked, its return path might be represented by the broken line 17, in which event the detector 18 rather than the detector 14 would be actuated by the ball during its return path. If the ball were sliced, as indicated by the broken lines 19 or 21, the detector 11 or the detector 8, respectively, rather than detector 14, would be actuated by the ball during its return path.

In this manner, it will be readily seen that, by noting the photo detector or detectors actuated by the ball travelling from the point 6 from which the ball is hit to the impact point 15 on the surface 9, and the photo detector or detectors actuated by the reflected ball, the amount of book or slice can readily be determined.

It is noted that the impact surface 9 may be of any suitable construction and configuration. Although it is preferable that the impact surface be substantially planar, it may, for example, be curved or angled so long as it is calibrated to predetermine the angle of reflection therefrom of a golf ball hit without spin from a known point of origin. Also, if the golf ball is to be hit from more than one known point of origin, the impact surface should be so calibrated for each known point of origin.

In the event the golf ball is to be hit from points of origin that may not be predetermined, a second row of detectors 110, shown in broken lines in FIG. 2, may be positioned between the first row of detectors l0 and the point or points of origin 6. This arrangement serves to provide an indication of a straight line path defined by the detectors in each row that are actuated as the ball approaches the impact surface 9 and as it rebounds therefrom.

As an illustrative example, FIG. 3 illustrates one embodiment of an apparatus for producing an output indicative of the amount of spin, e.g., hook or slice imparted to a golf ball, in accordance with the principles of the present invention. A series of resistors R1 through R32 are connected in series with a source, such as battery 26, and a variable resistor RA. Switches Sl through S32 are connected between the resistors R1 through R32 and bus 28. Switches S1 through S32 correspond to the row of 32 photo detectors in FIG. 2, and are normally open. One or more of the switches S1 through S32 are closed when light incident upon corresponding photo detectors is blocked by the passage of the golf ball. This may be accomplished, for example,

by means of relays (not shown). A variable voltage divider is formed by the resistances R1 through R32 and switches S1 through S32 in combination with battery 26, such that the configuration of the voltage divider connected to battery 26 corresponds to the photo detector which is actuated by the passage of the golf ball.

Switch SA2 associated with relay 30 is normally in the in" position as illustrated in FIG. 3. Thus, when the ball is hit and crosses the row of photo detectors 10, the actuated photo detector momentarily closes the corresponding switch of the switches S1 through S32 to produce a voltage at terminal 32 indicative of the closed switch. This voltage is stored on capacitor C1. The blocking or actuation of any one of the photo detectors 10, as the ball travels between the point of origin 6 and the impact surface 9, serves to energize relay 30. This moves switch SA2 to the out position and opens switch SAl, thereby placing variable resistor RA in the circuit.

As the ball rebounds from the impact surface 9 and again crosses the row of detectors to actuate another photo detector, this momentarily closes a different one of the switches S1 through S32 to produce a different voltage at point 32 which is applied to capacitor C2. Resistor RA is adjusted such that, when the ball is hit without spin to create an angle of incidence equal to the angle of reflection relative to a planar impact surface, the voltage produced at terminal 32, caused by the actuation of one of the photo detectors during the forward path of the ball, will be the same as the voltage produced at terminal 32 caused by the actuation of a second photo detector during the return path of the ball. This can be accomplished because the angle of incidence equals the angle of reflection for a ball hit without spin toward a planar impact surface, and thus the photo detector to be actuated during the return path can be predicted.

If side spin is imparted to the ball such that it is hooked or sliced, the voltage stored on capacitor C2 differs from that stored on capacitor C1, and the two voltages are compared on a comparator 34 which produces an output indicative of the voltage difference.

The operation of the apparatus of the present invention may be illustrated by way of an example and by referring to FIGS. 2 and 3. When a ball is hit from the point of origin 6 and travels to point on impact surface 9, the path of the ball crosses the row of photo detectors at the location of photo detector 16 in FIG. 2. This blocks the light incident upon photo detector 16 to produce an output. The output signal of photo detector l6 closes switch S16 and charges capacitor C1 through amplifier A1, to l6 volts, for example. Relay 30 is then energized to close switch SA1 and to move switch SA2 to the out position. If the ball is hit without any side spin, the angle of incidence will equal the angle of reflection and the reflected ball with block or actuate photo detector 14. Resistor. RA is adjusted such that when switch SAl is opened by energization of relay 30 and switch S14 is closed by the ball blocking light to photo detector 14, the voltage at terminal 30 is 16 volts rather than the 14 volts which would have occurred if resistor RA had not been put into the circuit. Thus, if the ball is hit without side spin, capacitor C2 is charged to 16 volts. The comparison in comparator 34 thus produces a zero output as shown in FIG. 3.

If, however, the ball were hooked and the path of the reflected ball blocked or actuated photo detector 18 rather than photo detector 14, switch R18 would be closed and capacitor C2 would be charged to 16/14 (18) 20.6 volts. Comparator 34 thus produces an output of 4.6 volts to move the pointer 40 to the right an appropriate amount to indicate the degree of hook. The greater the counterclockwise side spin or hook, the more to the right the pointer 40 would move. Similarly, in the case of a clockwise side spin or slice, the pointer 40 is moved to the left to indicate the degree of slice. The system then resets for actuation by the golf ball hit on the next shot.

It is noted that the apparatus of the present invention could be used to determine and indicate any type of spin imparted to a golf ball; e.g., spin about a substantially horizontal or vertical axis, depending on the arrangement of the detectors 10.

What is claimed is:

1. Apparatus for detecting the amount of spin imparted to a ball when hit in free flight from a point of origin, said apparatus comprising:

an impact surface positioned in the path of travel of the ball for rebounding the ball therefrom, detector means positioned between said point of origin and said impact surface for detecting the location of a first point at which the ball passes said detector means as it is travelling in flight toward said surface, and for detecting the location of a second point at which the ball rebounding in flight from said impact surface passes said detector means, without interfering with the flight of the ball, and

means responsive to the detection of said first and said second points for determining the amount of spin imparted to the ball.

2. The apparatus of claim 1, wherein said impact surface is substantially planar.

3. The apparatus of claim 1, wherein said impact surface is a screen.

4. The apparatus of claim 1, wherein said detector means and said last-mentioned means are so constructed and arranged to determine the amount of side spin imparted to the ball.

5. The apparatus of claim 1, wherein said lastmentioned means comprises indicator means connected to said detector means for indicating the amount of spin imparted to the ball.

6. The apparatus of claim 1 wherein said detector means comprises a plurality of sensors arranged in a row.

7. The apparatus of claim 6 wherein said sensors comprise photo detectors, and meansare provided to illuminate said photo detectors.

8. The apparatus of claim 6 wherein said means responsive to the detection of said first and second points comprises:

a. resistance means,

b. a plurality of switch means interconnected with said resistance means, each of said switch means corresponding to one of said plurality of sensors, whereby detection of the ball by one of said sensors operates said switch means to thereby change the resistance of said resistance means,

c. a voltage source connected to said resistance means, and

d. output means for detecting the voltage across said resistance means which varies in accordance with the variation of the resistance of said resistance means, said output means producing a signal indicative of the amount of spin imparted to the ball.

9. The apparatus of claim 8 wherein said resistance means and said plurality of switch means are interconnected to form a variable voltage divider having a configuration which changes in accordance with the operation of said switch means.

10. The apparatus of claim 8 wherein said output means includes storage means for storing a voltage corresponding to said first point and for storing a voltage corresponding to said second point, and means for comparing said stored voltages and for producing an output indicative of the comparison. 

1. Apparatus for detecting the amount of spin imparted to a ball when hit in free flight from a point of origin, said apparatus comprising: an impact surface positioned in the path of travel of the ball for rebounding the ball therefrom, detector means positioned between said point of origin and said impact surface for detecting the location of a first point at which the ball passes said detector means as it is travelling in flight toward said surface, and for detecting the location of a second point at which the ball rebounding in flight from said impact surface passes said detector means, without interfering with the flight of the ball, and means responsive to the detection of said first and said second points for determining the amount of spin imparted to the ball.
 2. The apparatus of claim 1, wherein said impact surface is substantially planar.
 3. The apparatus of claim 1, wherein said impact surface is a screen.
 4. The apparatus of claim 1, wherein said detector means and said last-mentioned means are so constructed and arranged to determine the amount of side spin imparted to the ball.
 5. The apparatus of claim 1, wherein said last-mentioned means comprises indicator means connected to said detector means for indicating the amount of spin imparted to the ball.
 6. The apparatus of claim 1 wherein said detector means comprises a plurality of sensors arranged in a row.
 7. The apparatus of claim 6 wherein said sensors comprise photo detectors, and means are provided to illuminate said photo detectors.
 8. The apparatus of claim 6 wherein said means responsive to the detection of said first and second points comprises: a. resistance means, b. a plurality of switch means interconnected with said resistance means, each of said switch means corresponding to one of said plurality of sensors, whereby detection of the ball by one of said sensors operates said switch means to thereby change the resistance of said resistance means, c. a voltage source connected to said resistance means, and d. output means for detecting the voltage across said resistance means which varies in accordance with the variation of the resistance of said resistance means, said output means producing a signal indicative of the amount of spin imparted to the ball.
 9. The apparatus of claim 8 wherein said resistance means and said plurality of switch means are interconnected to form a variable voltage divider having a configuration which changes in accordance with the operation of said switch means.
 10. The apparatus of claim 8 wherein said output means includes storage means for storing a voltage corresponding to said first point and for storing a voltage corresponding to said second point, and means for comparing said stored voltages and for producing an output indicative of the comparison. 